Suppressors are legal in Washington as long as they’re registered under the federal National Firearms Act. The state adds no permit, no separate registration, and no extra license on top of the federal process. What Washington does add is a separate law on assault weapons that quietly reshapes which firearms you’re allowed to buy as a suppressor host, and that’s where most buyers run into trouble.
Federal Registration Is the Whole State Authorization
The National Firearms Act of 1934 classifies suppressors as “firearms” and puts them under the authority of the Bureau of Alcohol, Tobacco, Firearms and Explosives.1Office of the Law Revision Counsel. 26 USC 5845 – Definitions2Bureau of Alcohol, Tobacco, Firearms and Explosives. National Firearms Act (NFA) Every suppressor in civilian hands has to be individually registered with the ATF, and the buyer pays a one-time $200 federal tax at the time of transfer. The tax hasn’t changed since 1934.
Washington’s weapons statute, RCW 9.41.250, makes it a gross misdemeanor to use any device that suppresses the noise of a firearm, unless the suppressor is legally registered and possessed under federal law.3Washington State Legislature. Washington Code 9.41.250 – Dangerous Weapons – Penalty The federal tax stamp is the whole of your state-level authorization. There’s no separate Washington application, no state permit, no additional fee.
Once you’ve got the stamp, you can use the suppressor for target shooting, home defense, and hunting. Hunting with a suppressor has been allowed in Washington since 2011.
Who Can’t Own One
Federal eligibility is the first filter. You have to be at least 21, a U.S. citizen or lawful permanent resident, and able to pass an FBI background check. Anyone federally prohibited from possessing firearms — convicted felons, people under domestic violence restraining orders, unlawful drug users — can’t own a suppressor either.
Washington layers its own disqualifications on top. Under RCW 9.41.040, you can’t possess any firearm, suppressor included, if you’ve been convicted of a serious offense or any other felony. Certain misdemeanor and gross misdemeanor convictions also bar possession, including domestic violence offenses, stalking, harassment, and second-degree animal cruelty. Involuntary commitment for a mental health condition is a disqualifier too, unless your firearm rights have been formally restored.4Washington State Legislature. Washington Code 9.41.040 – Unlawful Possession of Firearms – Penalties
How the Purchase Actually Works
You can’t pay for a suppressor and walk out with it. The suppressor stays with the dealer until the ATF approves the transfer.
Start with a dealer holding a Federal Firearms License and a Special Occupational Tax (a Class 3 or SOT dealer). The dealer collects payment for the suppressor and typically charges a transfer fee. You then complete ATF Form 4, the “Application for Tax Paid Transfer and Registration of Firearm,” with identifying information, fingerprint cards, and a passport-style photograph. Most dealers now submit the electronic version, eForm 4, which moves faster than paper. The $200 tax is paid when the form is filed.
The ATF runs the background check through the FBI. As of February 2026, the average processing time for an eForm 4 filed by an individual was 10 days, and 26 days for a trust.5Bureau of Alcohol, Tobacco, Firearms and Explosives. Current Processing Times Those numbers shift with application volume. When the ATF approves the transfer, the tax stamp goes back to the dealer, who calls you to pick up the suppressor.
The Assault Weapon Trap
This is where Washington buyers most often get caught. The suppressor is legal. The problem is what you attach it to.
Washington’s assault weapon law, RCW 9.41.390, prohibits the manufacture, import, distribution, and sale of firearms that meet the state’s “assault weapon” definition. Under RCW 9.41.010, a semiautomatic center-fire rifle with a detachable magazine qualifies as an assault weapon if it also has a sound suppressor attached or a threaded barrel designed to accept one. The same rule reaches semiautomatic pistols with detachable magazines and threaded barrels capable of accepting a silencer.6Washington State Legislature. Washington Code 9.41.010 – Definitions
The ban targets sale and distribution, not simple possession of firearms lawfully acquired before the law took effect in 2023. If you already owned a semiautomatic center-fire rifle with a detachable magazine and threaded barrel before the ban, you can still possess it and use a suppressor on it. What you can’t do is buy a new one from a Washington dealer to serve as a suppressor host. New buyers looking for something to shoot suppressed generally turn to bolt-action rifles, lever-action rifles, rimfire semiautomatic rifles, or shotguns. None of those fall under the assault weapon definition.
Individual Ownership vs. an NFA Trust
If you file the Form 4 as an individual, you’re the only person who can legally possess your suppressor. No one else in your household can use it, transport it, or have access to it without you present.
An NFA trust is a legal entity that owns the suppressor in your place. It names trustees who are authorized to possess and use the trust’s items, and beneficiaries who inherit them. Multiple trustees can access the suppressor independently. If something happens to one trustee, the trust keeps owning the items without a new transfer.
The tradeoff: every trustee (a “responsible person” in ATF language) has to submit photographs, fingerprints, and pass a background check when an NFA item is added to the trust. Trust filings also tend to take longer than individual ones. The trust document itself needs language specifically authorizing NFA ownership, and every trustee must be eligible to possess firearms under both federal and Washington law.
Penalties for Getting It Wrong
Using a suppressor that isn’t federally registered is a gross misdemeanor under RCW 9.41.250, punishable by up to 364 days in county jail, a fine of up to $5,000, or both.3Washington State Legislature. Washington Code 9.41.250 – Dangerous Weapons – Penalty7Washington State Legislature. Washington Code 9A.20 – Classification of Crimes Selling or distributing a firearm that meets the assault weapon definition is also a gross misdemeanor under RCW 9.41.390, with the same maximum exposure.
The federal side is heavier. Possessing an unregistered NFA firearm, suppressors included, is a federal felony under 26 U.S.C. 5871, with up to 10 years in federal prison and a fine of up to $10,000.8Office of the Law Revision Counsel. 26 USC 5871 – Penalties There’s no way to retroactively register a suppressor you already have. If it wasn’t registered before you took possession, it can’t be registered after.2Bureau of Alcohol, Tobacco, Firearms and Explosives. National Firearms Act (NFA)
Taking a Suppressor Out of State
Federal law requires ATF pre-approval on Form 5320.20 to transport certain NFA items across state lines, but that requirement is limited to machine guns, short-barreled rifles, short-barreled shotguns, and destructive devices.9Office of the Law Revision Counsel. 18 USC 922 – Unlawful Acts Suppressors aren’t on that list. You can drive a registered suppressor from Washington into another state without filing Form 5320.20.
The catch is the destination. A handful of states ban civilian suppressor possession outright, and arriving there with a legally registered Washington suppressor is still a serious criminal offense. Federal registration doesn’t override a state ban. Check the law of every state you plan to travel through before you leave.